Place the cooked macaroni in a 3 1/2-quart (or larger) slow cooker that has been coated with nonstick cooking spray. Add 3 cups cheese, milks, eggs and seasonings to the macaroni. Mix well. Sprinkle with the remaining 1 cup cheese, then cover and cook on the low setting for 5 to 6 hours or until the mixture is firm and golden around the edges.
Do not remove the cover or stir until the mixture has finished cooking.